Machine tool travel indicator



April 1965 k. D. PEELER 3,177,589

MACHINETOOL TRAVEL INDICATOR Filed March 12, 1965 i 2 Sheets-Sheet l INVENTOR. ROBERT D. PEELER ATTORNEY April 13, 1965 R. D. PEELER 3,177,589

'- MACHINE TOOL TRAVEL INDICATOR Filed March 12, 1963 .2 Sheets-Sheet 2 FIG. 2

INVENTOR. ROBERT D. PEELER EZLMJ ATTORNEY The casing is fixedly mounted of theframe thereof. The drive United States Patent Ofi ice 3,177,589 Patented Apr. 13, 1965 3,177,589 MACHINE TOOL TRAVEL INDECATGR Robert D. Peeler, Inglewood, Caiifi, assignor to Dial Precision Machined Products Co. Inc., Hermosa Beach, Calif., a corporation of California Filed Mar. 12, 1963, Ser. No. 264,506 7 Claims. (Cl. 33-172) This invention relates to a machine tool travel indicator device and more particularly to such a device which enables the precise positioning of relatively movable members of a machine tool.

In performing precision machining, it is essential that the precise position of the movable portion of the tool relative to a predetermined reference point be ascertained. Devices of the prior art for accomplishing this end result have either tended to be of limited accuracy or overly complicated and somewhat unreliable in their operation.

Further, where highly precise measurements are to be made, it is essential that the critical working parts of the measuring instrument be protected from dirt, metal particles and other such factors which might impair the ac- I curacy of the measurements. Devices of the prior art have tended to keep many of the essential working parts in such a position and exposed condition that they are subject to this type of external influence. Further, many I devices of the prior art tend to have play in the coupling system between the drive input sensor and the indicator mechanism, thereby impairing the accuracy of the measurements made.

The device of this invention overcomes the shortcomings of the prior art devices in providing a machine tool indicator device in which the critical Working parts are isolated from external elfects by means of a closed case. The coupling mechanism is spring-loaded between the indicator device and the input sensor so that there is no significant play between these two points. The mechanism involved is relatively simple yet capable of highly accurate measurements.

It is therefore an object of this invention to provide an improved machine tool travel indicator device.

Itis a further object of this invention to provide a machine tool travel indicator device capable of higher reliability operation than prior art devices.

It is still a further object of this invention to provide a machine tool travel indicator device of very simple construction which is capable of highly accurate measurements.

It is still a further object of this invention to facilitate I the accurate measurement of machine tool travel.

Other objects of this invention will become apparent from the following description taken in connection with the accompanying drawings of which:

FIG. 1 is a perspective view of a preferred embodiment of the device of the invention, and

FIG. 2 is a sectional view of the embodiment of the invention shown in'FIG. 1.

In the device of the invention a drive rod having a plurality of notches formed therein is slideably mounted in a'casing. This drive rod has a plurality of notches formed therein which are spaced a predetermined distance from each other. A drive head which acts as a position sensor is rotatably mounted on the rod at one end thereof. generally on a stationary portion of the machine tool such as for example, a portion head is positioned so that it abuts against a movable portion of themachine tool such as for example, the carriage thereof. A lineal dis placement indicator is fixedly mountedon the casing of I head. Mounted on the drive bar is an actuator pin which moves with the drive bar and abuts against the input plunger of the displacement indicator.

Also mounted on the drive bar is a pawl which is shaped so that it mates with the notches in the drive rod. The pawl abuts against a vertical wall of the notch which is towards the drive head, thereby engaging the rod and causing the drive bar to travel with the rod when the drive head is driven by the machine tool carriage. The drive bar in turn actuates the displacement indicator so that displacement of the drive head is transferred to the input f this indicator. The drive rod does not engage the pawl when it is moved in the direction opposite to the drive direction.

Referring nOW to FIGS. 1 and 2 a preferred embodiment of the device of the invention is shown. Drive rod 11 is slideably mounted in casing 12. Drive rod 11 has a plurality of notches 14 formed therein which are spaced an equal distance from each other. This distance may, for example, be one inch for utilization with a standard displacement indicator. Mounted on one end of drive rod 11 is a drive head 15. Drive head 15 is mounted for rotation on the rod with a spring actuated ball 17 being retained in the head which falls into a series of mating spherical grooves 18 formed around the circumference of the rod. The grooves 18 are positioned at distinct positions around the rod to provide predetermined resting points for head 15.

Head 15 has a plurality of adjustable actuator pins 2-0 threadably mounted therein. These pins can be adjusted to extend various distances from the drive head as desired. The actuator pins 20 may be positioned against various object-s on the carriage to provide predetermined reference starting positions. Each actuator pin thus can be utilized for a different starting position by rotation to bring it into abutment against the particular desired reference object.

Slideably mounted within case 12 is drive bar 30. Fixedly mounted in casing 12 is lineal displacement indicator 32. This displacement indicator may, for example, be one manufactured by the Starrett Company of Athol, Massachusetts having a total range of one inch and capable of making measurements within a thousandth of an inch. Drive bar 30 has an actuator pin 35 mounted thereon which abuts against the input plunger 39 of the displacement indicator. Input plunger 39 is positioned within a channel 42 formed in the casing.

Also mounted in the drive bar is pawl 40 which is spring-urged against drive rod 11 by spring 41. Pawl 40 has a forward edge which mates with the forward edges of each of grooves 14. The rear edge of pawl 40 is-rounded so that it slides along the rear edges of notches 14 when the drive rod 11 is moved from right to left in the device as illustrated in FIGS. 1 and 2. When drive rod 11 is driven to the right with the actuation of drive head 15 by the machine tool member against which one or more of the pins 20 abuts, the forward edge of pawl 40 will catch against the forward edge of one of the grooves 14 of the rod, and drive bar 30 will be driven along with the drive head. Drive bar 30 will carry input plunger 39 along with it by virtue of the action of pin 35. Thus, the input drive will be transmitted to displacement indicator 32.

Drive bar 30 is urged towards drive head 15 by spring 40 which is of relatively heavy construction and maintains the leading edge of pawl 40 firmly against the leading edge of one of the notches 14. This minimizes the play in the drive system and thereby enhances the accuracy of the measurements made.

Rod 11 can be moved past the pawl 40 in the general direction from left to right in the device as illustrated, by rotating the rod 11 to a position from that shown in the figures. Pawl 40 will then abut against the unnotches 14 are vertically positioned .when the rod is in its normal operatingipositionthereby minimizing the possibility of scrap filings catching in these notches: and impairing the operation of the mechanism; g In the utilization of the device of the invention witha machine tool such as a lathe, the casing 12 may be fixedly attached to a normally stationary portion of the lathe such as the headstock. 'Headv15 is'then positioned; so that .it abuts against a reference memberon thetlathe carriage. Movementof the carriage I will be accurately indicated towards 'casing12, then, on displacement indicator 32. Precise measurements to within one thousandth of an inch have been made withoperative embodimentsof the de-, vice of the invention; f Closer measurements could be made with a displacement indicator having a higher definition.

will not catch thereon.

The device ofthis invention thus provides a simpleyet 1 highly accurate instrument for measuring'the travel of a :While the device of the invention has been;

machine tool. 7 7 described and illustrated in detailit is to be clearly'understood that thisis .25 intended by way'ofillustrationand exampleonly and'is not to be'takenby way of limitation,

the-spirit and scope of thisinvention being limited only by the terms a: the following claims. I claim:

a casing,

a drive rod'having a plurality of notches formed there; H

inslideably mounted in said casing, v

a'drivei head mounted on said'rod atone end thereon fixedly jrriounted' in said spring means for urging said bar towards said"drive mounted on vsaid drive bar, said actuhead, an actuator pin ator pin abut-ting; against the input plunger of said displacement'indicator, a pawl mounted in said drive bargand l l r springgmeans for urging said pawlfagjainstgsaid drive rod, said pawl with the notches or said drive rod, ,7 whereby when said drive 7 casing; said pawl .I displacement"indicator: is actuated in accordance with'relative movemeut b'etween said drivevhe ad and said casing.

V i 12. Thedevice as recitedjin l u/herein jhas a-channel formed therein .ment indicator plunger, said .plungerbeingf ully contained withinisaidch'annelr t t v v V I 3.; A; machine "tool travel indicator device comprising a a i a drive rod having a plurality otinotehesiformfld thereinslideably mountedin said'easing,v

f adrivehead mountedon said rodatoneendthereof,

head is driventowards said engages said vdrive rod and said,

30 1. A machine tool travel indicator device comprising being adapted for'mating-engagement 31? spring means fory-urgingsa dicator, k

1 edge mountedin said'd'rive bar, and a 7 spring means for urging said' pawl against said drive a rod with the leading edge of said pawlin'mating v engagementwith the, f rward edges of the notches of said drive'rod, 1 I a whereby when'saidjdrive head is driven towards said casing, said'pawlj engages said drive rod ,and said displacement indicatoris acuated in accordance with relative movement between said drive, head and said casing. p 4. .The device asrecited in claim 3 wherein said drive head is'rotatabl'y mounted on saidlrod and has a plurality of position pinspositionally adjustable, relative thereto along axes parallel to theq'longitudinal axis of said'rod. w A machine tool travel indicator device comprising ;a:cas1ng, 1' i v x .a drive rod having a plurality of notches Iformed therein slideably mounted in saidLcas'ing, said notches being spaced along-'said-md a predetermined distance frorn'each other,f a drive head'rotatably mounted on saidrod, at one end thereof, said'drive head having a plurality of, position pins adjustable relative thereto along axes parallel'to thelongitudinal axisofisaid rod,

a lineali displaceme'nt indicator fixedly mounted in said casing, said indicator having an, input plunger, a drive bar-slideabljmounted in said casing, spring means for urging said bar 'towardssaid drive head, r A an actuator pin mounted on said drive bar, said actu-' ator'pin abutting against the input plunger of said displacement indicator, l I Y ,-a pawl mountedi'n said drive bar, and t pawl against said drive .rod, said pawl being 'adaptedfor'mating engagement withtheinotches of said drive rod; 6. 'Ihe devicea'sirecited-l cl m5 herein said pawl has a'leading edge'shaped' forv m 'ting enga ge'ment with the'lcading edges ofsaid notches,

the rear edge of: said pawl being rounded .toslide over' therear edges of said for. receiving said dis la 5-5 p notches. I

zflzdssr j L4/g1 f usnaie; @ISAAQ pIs n, Primv ryjjExdminer "7 Ihe devicefas recitediin iilairh-S wherein said drive bar; saidfdhive rod, a'nd s'aid input'plung'er 'are'slideably imounted for motion along axes parallel: to each other.

1 References Cited'by the-Exaniinen l a UNITED;STATESTATENTS; Y 33-'-125 ment'with the inputplunger'of said displacement m a pawlhaving asteep leading edge and a rounded rear 

1. A MACHINE TOOL TRAVEL INDICATOR COMPRISING A CASING, A DRIVEN ROD HAVING A PLURALITY OF NOTCHES FORMED THEREIN SLIDEABLY MOUNTED IN SAID CASING, A DRIVE HEAD MOUNTED ON SAID ROD AT ONE END THEREOF, A LINEAL DISPLACEMENT INDICATOR FIXEDLY MOUNTED IN SAID CASING, SAID INDICATOR HAVING AN INPUT PLUNGER, A DRIVE BAR SLIDEABLY MOUNTED IN SAID CASING, SPRING MEANS FOR URGING SAID BAR TOWARDS SAID DRIVE HEAD, AN ACTUATOR PIN MOUNTED ON SAID DRIVE BAR, SAID ACTUATOR PIN ABUTTING AGAINST THE INPUT PLUNGER OF SAID DISPLACEMENT INDICATOR, A PAWL MOUNTED IN SAID DRIVE BAR, AND SPRING MEANS FOR URGING SAID PAWL AGAINST SAID DRIVE ROD, SAID PAWL BEING ADAPTED FOR MATING ENGAGEMENT WITH THE NOTCHES OF SAID DRIVE ROD, WHEREBY WHEN SAID DRIVE HEAD IS DRIVEN TOWARDS SAID CASING, SAID PAWL ENGAGES SAID DRIVE ROD AND SAID DISPLACEMENT INDICATOR IS ACTUATED IN ACCORDANCE WITH RELATIVE MOVEMENT BETWEEN SAID DRIVE HEAD AND SAID CASING. 